1. Field of the Invention
This invention relates to a process of improving washfastness of dyed nylon textile materials by treatment with water soluble polymeric textile treating agents.
2. Description of the Prior Art
In the dyeing of nylon textile materials, acid dyes selected for minimum barre' and warpiness often have poor washfastness. Washfastness of dyed material may be improved by back tanning, i.e., treatment with 1 to 2% tannic acid and 1 to 2% of 85% formic acid at 70.degree. C. for 15 to 20 minutes; 1 to 2% tartar emetic is then added and treatment continued for an additional 15 to 20 minutes at 70.degree. C. A simpler procedure involves contacting dyed material with a liquor containing 3 to 5% of a phenolic derivative such as Cibatex PA, Tanninol WR or Nylofix P and 2% of 85% formic acid for 15 to 30 minutes at 70.degree. to 90.degree. C.
Swiss 283,402--G. R. Geigy, A.G. shows use of synthetic tanning agents as reserving agents for polyamide or polyurethane fibers in blends with wool or silk. These agents are prepared by acid condensation of naphthalenesulfonic acid, dihydroxy diphenyl sulfone and formaldehyde using these components at molar ratios such as 1:1:1, 1:1.5:1 and 1:0.7:0.75. They can be added to the dyebath or used to pretreat textile materials which are then rinsed and dyed. Additional information may be found in Chemical Abstracts 47, 10861i (1953). A similar product, Erional NW, is described in the 1965 Technical Manual of the American Association of Textile Chemists and Colorists on page E-140. This product is a mixed condensate of naphthalene monosulfonic acids with dihydroxy diphenylsulfones and formaldehyde which is used as a reserving agent on nylon and a fixative for certain acid colors on nylon.
U.S. Pat. No. 3,790,344--Frickenhaus et al, Feb. 5, 1974 shows washfastness of dyed synthetic polyamide textile material may be improved by aftertreating dyed material with condensation products which are barely water-soluble higher molecular weight polymers prepared in aqueous medium using dihydroxy diphenyl sulfone, formaldehyde and naphthalenesulfonic acid using components in molar ratios of 1:0.7-1.1:0.7-0.2. These condensation products are reported to be better than water soluble tanning agents (water soluble condensation products of dihydroxy diphenyl sulfone, formaldehyde and naphthalenesulfonic acid) in improving washfastness, but they are not useful as tanning agents because they can only be dissolved in hot water and form opalescent solutions.